Low molecular weight poly(acrylic acid) as a salt scaling inhibitor in oilfield operations

Poly(acrylic acid) (PAA) samples with molecular weights between 820 and 2950 were synthesized by a solution polymerization process using an initiating redox system. The obtained PAAs were then screened for their ability to inhibit salt scale formation. In this screening system, salt scale was formed by injecting pit water into the oil. The salt scale inhibition efficiency was higher for PAAs at a higher concentration and for lower molecular weight PAAs. A reduction of pH, extension of stirring time, or an increase in temperature caused the inhibition efficiency of the PAAs to drop. An optimal inhibition efficiency of 98.70% was observed using a PAA with a molecular weight of 820 at a concentration of 20 ppm, at 20 °C, while being stirred for 1 h at a pH of 6.029.